River Blackfish, Gadopsis marmoratus Richardson 1848

Other Names: Blackfish, Duat, Freshwater Blackfish, Marble Cod, Marbled River Cod, Slimy, Slippery, Tasmanian Blackfish

A River Blackfish, Gadopsis marmoratus, from Blackfish Creek, Refuge Cove, Wilsons Promontory, Victoria. Source: Ken Harris. License: CC by Attribution-NonCommercial

Summary:

River Blackfish are highly variable in colour, including mottled yellowish, brownish-green, dark brown or greyish with irregular blotches on the upper sides. The lower part of the body ranges from pale bluish-brown, to yellow or purple. The body is covered in very small scales and usually covered in a heavy coat of slime.

Genetic studies indicate that Gadopsis marmoratus is a complex of several cryptic species (Unmack et al. 2017).

Cite this page as:

Bray, D.J. 2024, Gadopsis marmoratus in Fishes of Australia, accessed 17 May 2025, https://fishesofaustralia.net.au/home/species/3877

River Blackfish, Gadopsis marmoratus Richardson 1848

More Info

Distribution	Upper reaches of most rivers in the Murray-Darling Basin, and in coastal rivers from eastern Victoria (Cann River) to the mouth of the Murray River in South Australia, and rivers across northern Tasmania. In Victoria, the species occurs in tributaries of the Murray system and in south-flowing streams, although absent from many smaller coastal streams, such as those in Otway Ranges. Unsanctioned introductions have also occurred in some southern Tasmanian streams, such as the Derwent and Huon rivers. River Blackfish prefers clear, gently flowing streams with abundant cover such as rock cover, logs, snags, woody debris and rocks.
Features	The River Blackfish is slender with rounded fins, a large head with a rounded snout that slightly overhangs the large mouth, and pelvic fins with a single ray positioned below the gill openings.
Feeding	Ambush predators, feeding on fishes, crustaceans and aquatic insects.
Biology	The species breeds in late spring to early summer, and females lays large, adhesive eggs in submerged hollow logs, snags and amongst boulders. Males guard the eggs and newly hatched larvae. After hatching, the larvae remain tethered to the egg case until they have used up their yolk sac and are ready to commence feeding by mouth. This adaptation presumably prevents the larvae being washed downstream by the currents.
Fisheries	A popular angling fish (although more so historically) in parts of its range, reportedly with sweet-tasting flesh.
Conservation	Protected in South Australia, Queensland and New South Wales, with closed seasons, size and bag limits in Victoria, and size and bag limits in Tasmania. Populations have been affected by increased siltation on streams, desnagging of rivers, changed stream flows from the construction of dams and weirs, and competition from introduced species such as Redfin and trout.
Remarks	The name "Duat" is the Woiwurrung word for this species. The Woiwurrung is the language spoken by the Wurundjeri people of the Kulin Nation of Central Victoria.
Etymology	The specific name is from the 3atin marmoratus (= marbled), in reference to the marbled colour pattern of this species.
Species Citation	Gadopsis marmoratus Richardson 1848, Zool. Voy. Erebus and Terror: 122. Type locality: Rivers in the southern part of Australia [Murray River, South Australia].
Author	Bray, D.J. 2024
Resources	Atlas of Living Australia Australian Faunal Directory Catalog of Fishes

River Blackfish, Gadopsis marmoratus Richardson 1848

References

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Campbell, M.A., Hammer, M.P., Adams, M., Raadik, T.A. & Unmack, P.J. 2024. Evolutionary relationships and fine-scale geographic structuring in the temperate percichthyid genus Gadopsis (blackfishes) to support fisheries and conservation management. Molecular Phylogenetics and Evolution 199: 108159 https://doi.org/10.1016/j.ympev.2024.108159

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Davies, P.E. 1989. Relationships between habitat characteristics and population abundance for Brown Trout, Salmo trutta L., and Blackfish, Gadopsis marmoratus Rich., in Tasmanian streams. Australian Journal of Marine and Freshwater Research 40: 341-359. https://doi.org/10.1071/MF9890341

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Hammer, M.P., Unmack, P.J., Adams, M., Raadik, T.A., Johnson, J.B. 2014. A multigene molecular assessment of cryptic biodiversity in the iconic freshwater blackfishes (Teleostei: Percichthyidae: Gadopsis) of southeastern Australia. Biological Journal of the Linnean Society 111: 521–540. https://doi.org/10.1111/bij.12222

Huey, J.A, Balcombe, S.R., Real, K.M. & Hughes, J. 2017. Genetic structure and effective populations size of the most northern population of the Australian River Blackfish, Gadopsis marmoratus (Richardson, 1848): implications for long-term population viability. Freshwater Science 36: 113-123. https://doi.org/10.1086/690557

Jackson P.D. 1978. Spawning and early development of the river blackfish, Gadopsis marmoratus Richardson (Gadopsiformes: Gadopsidae), in the McKenzie River, Victoria. Marine and Freshwater Research 29: 293-298. https://doi.org/10.1071/MF9780293

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Kuiter, R.H. 2018. Pictorial guide to Victoria's freshwater fishes. E-version Part 1. Aquatic Photographics, Seaford, Victoria, Australia: 1-110. (considers Gadopsis gracilis McCoy to be a valid species; considers G. gibbosus McCoy to be a questionable synonym of G. gracilis).

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McCoy, F. 1879. Prodromus of the Zoology of Victoria. Decade 3. Melbourne : George Robertson Vol. 1 1-50 pls 21-30. (p. 39, pl. 27(2), described as Gadopsis gracilis, type locality Yarra River, Victoria); p. 41, as Gadopsis gibbosus, type locality - Bunyip River, Gippsland, Victoria) See ref at BHL

Merrick, J.R. & Schmida, G.E. 1984. Australian Freshwater Fishes Biology and Management. Sydney : J.R. Merrick 409 pp. figs 280 col. figs.

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Richardson, J. 1848. Ichthyology. 75-139 pls 42-43 & 44 (parts), 45-52, 53 in Richardson, J. & Gray, J.E. (eds). The Zoology of the Voyage of H.M.S. Erebus and Terror under the Command of Captain Sir James Clark Ross, R.N., F.R.S., during the years 1839–43. London : Smith, Elder & Co. Vol. 2 139 pp. See ref online

Ryan, S.G., Miller, A.D. & Austin, C.M. 2004. Allozyme variation and taxonomy of the river blackfish, Gadopsis marmoratus Richardson, in western Victoria. Proceedings of the Royal Society of Victoria 116(2): 191-200. https://biostor.org/reference/257597 Also, see ref at BHL

Sanger, A.C. 1984. Description of a new species of Gadopsis (Pisces: Gadopsidae) from Victoria. Proceedings of the Royal Society of Victoria 96: 93-97. https://biostor.org/reference/259608

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Steindachner, F. 1884. Ichthyologische Beiträge (13)1. Beiträge zur Kenntniss der Fische Australiens. Sitzungsberichte der Akademie der Wissenschaften in Wien. Mathematisch-Naturwissenschaftliche Klasse 88(1): 1065-1108 figs 1-8 (described as Gadopsis fuscus, type locality - freshwaters of South Australia). See ref at BHL

Turschwell, M.P., Stewart-Koster, B., Balcombe, S.R., et al. 2020. Multiscale relationships between stream temperature and juvenile recruitment in an imperilled freshwater fish. Marine and Freshwater Research 71: 1269-1280. https://doi.org/10.1071/MF19149

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Unmack, P.J., Sandoval-Castillo, J., Hammer, M.P., Adams, M., Raadik, T.A., Beheregaray, L.B. 2017. Genome-wide SNPs resolve a key conflict between sequence and allozyme data to confirm another threatened candidate species of river blackfishes (Teleostei: Percichthyidae: Gadopsis). Molecular Phylogenetics and Evolution 109: 415-420 https://doi.org/10.1016/j.ympev.2017.02.013Abstract